Bacterial predation on T4 phages

Godon, Jean-Jacques; Bize, Ariane; Ngo, Hoang; Cauquil, Laurent; Almeida, Mathieu; Petit, Marie Agnès; Zemb, Olivier

Background Bacterial consumption of viruses has never yet been reported, even though bacteria feed on almost anything. Viruses are omnipresent predators for all organisms, but have no acknowledged active biocontrol. The viral biomass undoubtedly reintegrates the trophic cycles, however the mechanisms of this phase still remain unknown. Methods Here, we used stable isotope probing with 13C labelled T4 phages to monitor the increase of density of the bacterial DNA concomitant with the decrease of plaque forming units. We used 12C T4 phages as control. Results T4 phage disappearance in wastewater sludge was found to occur mainly through predation by Aeromonadacea. Phage consumption also favours significant in situ bacterial growth. Furthermore, an isolated strain of Aeromonas was observed to grow on T4 phages as sole source of carbon, nitrogen and phosphorus. Conclusions bacterial species are capable of consuming bacteriophages in situ, which is likely a widespread and underestimated type of biocontrol.This assay is anticipated as a starting point for harnessing the bacterial potential in limiting the diffusion of harmful viruses within environments such as gut or water.